A novel sensor for detection of oil condition and contamination based on a thermal approach

Oil condition and contamination can be a major issue in lubrication systems such as aircraft, automobiles etc. Lubricating or cooling oil contamination occurs when metallic or non-metallic particles are produced due to wear of machine components and these are not captured by the filter system. Furthermore, thermal stressing causes oxidation and thereby degradation of the oil. Liquid contamination can occur from water condensation or fuel from heat exchangers. These can cause degradation of the oil and reduce the lubricating properties and clogg oil paths and accelerate the wear of moving parts. On-line oil condition monitoring systems are important for preventive maintenance especially for aircraft engine bearings, aviation gearboxes etc. Current on-line oil condition monitoring sensors are mainly eddy current, optical based. These sensors have a major drawback that they are prone to surface contamination and non-linearity. The gauges are also not sensitive enough to detect extremely small particulates or are prone to false detection such as trapped bubbles. A new sensor has been developed using thin film heat transfer sensors that can detect any form of contamination in oil such as metal, nonmetals, oxidation, liquids etc. The sensor works on the principle of measuring the thermal product of the material, as the composition of the material in contact with the sensor changes the thermal product changes and can be detected. The sensor can be used for both on-line and in-line condition monitoring and has been demonstrated to be robust. Initially, lab based tests were carried out to optimise the system for sensitivity and signal to noise ratio. The sensor has been demonstrated to detect 0:25% of contaminants by mass. Experiments were carried out by seeding metallic and non-metallic particles of various sizes to an engine oil system to validate its performance.Papers presented to the 12th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Costa de Sol, Spain on 11-13 July 2016

Rise time evaluation of the heat flux microsensor (HFM) on a hot-air-gun test rig

Paper presented at the 8th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Mauritius, 11-13 July, 2011.Investigating the heat transfer inside internal combustion engines is key in the search for higher efficiency, higher power output and lower emissions. To understand the process and to validate model predictions, heat flux measurements inside an engine have to be conducted. In previous works, we have always used a commercially available thermopile to measure the heat transfer in a hydrogen combustion engine, but its large dimensions pose concerns about the sensor’s response time. Therefore, measurements have been done on a calibration rig with a hot air flow as heat source. This paper presents a comparison of the rise time of the thermopile with that of an alternative sensor developed for heat transfer measurements in gas turbines. The papers results in an increased confidence in the thermopile sensor, because its response time is at least as good as that of the alternative sensor. The results do show that the reproducibility of the test rig can be improved. Moreover, due to fluctuations in the heat flux level generated by the source, only the order of magnitude of the measured heat flux of two different experiments was comparable. Therefore, a new calibration rig will be developed to improve the reproducibility and to increase stability of the heat flux level of the heat source.mp201

Performance of novel VUV-sensitive Silicon Photo-Multipliers for nEXO

Liquid xenon time projection chambers are promising detectors to search for neutrinoless double beta decay (0$\nu \beta \beta$), due to their response uniformity, monolithic sensitive volume, scalability to large target masses, and suitability for extremely low background operations. The nEXO collaboration has designed a tonne-scale time projection chamber that aims to search for 0$\nu \beta \beta$ of \ce{^{136}Xe} with projected half-life sensitivity of $1.35\times 10^{28}$~yr. To reach this sensitivity, the design goal for nEXO is $\leq$1\% energy resolution at the decay $Q$-value ($2458.07\pm 0.31$~keV). Reaching this resolution requires the efficient collection of both the ionization and scintillation produced in the detector. The nEXO design employs Silicon Photo-Multipliers (SiPMs) to detect the vacuum ultra-violet, 175 nm scintillation light of liquid xenon. This paper reports on the characterization of the newest vacuum ultra-violet sensitive Fondazione Bruno Kessler VUVHD3 SiPMs specifically designed for nEXO, as well as new measurements on new test samples of previously characterised Hamamatsu VUV4 Multi Pixel Photon Counters (MPPCs). Various SiPM and MPPC parameters, such as dark noise, gain, direct crosstalk, correlated avalanches and photon detection efficiency were measured as a function of the applied over voltage and wavelength at liquid xenon temperature (163~K). The results from this study are used to provide updated estimates of the achievable energy resolution at the decay $Q$-value for the nEXO design

Statistical mechanics of itinerant-electron magnets

SIGLEAvailable from British Library Document Supply Centre- DSC:DX175549 / BLDSC - British Library Document Supply CentreGBUnited Kingdo

Reflectivity and PDE of VUV4 Hamamatsu SiPMs in liquid xenon

© 2020 IOP Publishing Ltd and Sissa Medialab. Understanding reflective properties of materials and photodetection efficiency (PDE) of photodetectors is important for optimizing energy resolution and sensitivity of the next generation neutrinoless double beta decay, direct detection dark matter, and neutrino oscillation experiments that will use noble liquid gases, such as nEXO, DARWIN, DarkSide-20k, and DUNE . Little information is currently available about reflectivity and PDE in liquid noble gases, because such measurements are difficult to conduct in a cryogenic environment and at short enough wavelengths. Here we report a measurement of specular reflectivity and relative PDE of Hamamatsu VUV4 silicon photomultipliers (SiPMs) with 50 μm micro-cells conducted with xenon scintillation light (∼175 nm) in liquid xenon. The specular reflectivity at 15ˆ incidence of three samples of VUV4 SiPMs is found to be 30.4±1.4%, 28.6±1.3%, and 28.0±1.3%, respectively. The PDE at normal incidence differs by ±8% (standard deviation) among the three devices. The angular dependence of the reflectivity and PDE was also measured for one of the SiPMs. Both the reflectivity and PDE decrease as the angle of incidence increases. This is the first measurement of an angular dependence of PDE and reflectivity of a SiPM in liquid xenon11Nsciescopu

Development of a 127^{127}Xe calibration source for nEXO

International audienceWe study a possible calibration technique for the nEXO experiment using a $^{127}$Xe electron capture source. nEXO is a next-generation search for neutrinoless double beta decay (0νββ) that will use a 5-tonne, monolithic liquid xenon time projection chamber (TPC). The xenon, used both as source and detection medium, will be enriched to 90% in $^{136}$Xe. To optimize the event reconstruction and energy resolution, calibrations are needed to map the position- and time-dependent detector response. The 36.3 day half-life of $^{127}$Xe and its small Q-value compared to that of $^{136}$Xe 0νββ would allow a small activity to be maintained continuously in the detector during normal operations without introducing additional backgrounds, thereby enabling in-situ calibration and monitoring of the detector response. In this work we describe a process for producing the source and preliminary experimental tests. We then use simulations to project the precision with which such a source could calibrate spatial corrections to the light and charge response of the nEXO TPC

Performance of novel VUV-sensitive Silicon Photo-Multipliers for nEXO

Liquid xenon time projection chambers are promising detectors to search for neutrinoless double beta decay (0$\nu \beta \beta$), due to their response uniformity, monolithic sensitive volume, scalability to large target masses, and suitability for extremely low background operations. The nEXO collaboration has designed a tonne-scale time projection chamber that aims to search for 0$\nu \beta \beta$ of \ce{^{136}Xe} with projected half-life sensitivity of $1.35\times 10^{28}$~yr. To reach this sensitivity, the design goal for nEXO is $\leq$1% energy resolution at the decay $Q$-value ($2458.07\pm 0.31$~keV). Reaching this resolution requires the efficient collection of both the ionization and scintillation produced in the detector. The nEXO design employs Silicon Photo-Multipliers (SiPMs) to detect the vacuum ultra-violet, 175 nm scintillation light of liquid xenon. This paper reports on the characterization of the newest vacuum ultra-violet sensitive Fondazione Bruno Kessler VUVHD3 SiPMs specifically designed for nEXO, as well as new measurements on new test samples of previously characterised Hamamatsu VUV4 Multi Pixel Photon Counters (MPPCs). Various SiPM and MPPC parameters, such as dark noise, gain, direct crosstalk, correlated avalanches and photon detection efficiency were measured as a function of the applied over voltage and wavelength at liquid xenon temperature (163~K). The results from this study are used to provide updated estimates of the achievable energy resolution at the decay $Q$-value for the nEXO design

Performance of novel VUV-sensitive Silicon Photo-Multipliers for nEXO

Liquid xenon time projection chambers are promising detectors to search for neutrinoless double beta decay (0$\nu \beta \beta$), due to their response uniformity, monolithic sensitive volume, scalability to large target masses, and suitability for extremely low background operations. The nEXO collaboration has designed a tonne-scale time projection chamber that aims to search for 0$\nu \beta \beta$ of \ce{^{136}Xe} with projected half-life sensitivity of $1.35\times 10^{28}$~yr. To reach this sensitivity, the design goal for nEXO is $\leq$1% energy resolution at the decay $Q$-value ($2458.07\pm 0.31$~keV). Reaching this resolution requires the efficient collection of both the ionization and scintillation produced in the detector. The nEXO design employs Silicon Photo-Multipliers (SiPMs) to detect the vacuum ultra-violet, 175 nm scintillation light of liquid xenon. This paper reports on the characterization of the newest vacuum ultra-violet sensitive Fondazione Bruno Kessler VUVHD3 SiPMs specifically designed for nEXO, as well as new measurements on new test samples of previously characterised Hamamatsu VUV4 Multi Pixel Photon Counters (MPPCs). Various SiPM and MPPC parameters, such as dark noise, gain, direct crosstalk, correlated avalanches and photon detection efficiency were measured as a function of the applied over voltage and wavelength at liquid xenon temperature (163~K). The results from this study are used to provide updated estimates of the achievable energy resolution at the decay $Q$-value for the nEXO design